1. Field of the Invention
The present invention relates to an air bag system for vehicles, and more particularly to a passenger air bag system for vehicles, which is capable of preventing eccentric expansion of a cushion when a collision of the vehicle occurs by improvement of the installation structure of an air bag housing and an inflator.
2. Description of the Related Art
Generally, an air bag system for vehicles is mounted in front of a driver seat or a passenger seat in such a manner that a cushion of the air bag system is instantly expanded when a collision of the vehicle occurs for protecting a driver or a passenger from injury.
The air bag systems may be classified into a driver air bag system and a passenger air bag system. The driver air bag system is mounted to the steering wheel of the vehicle for protecting the driver from injury. The passenger air bag system is mounted to an instrument panel of the vehicle disposed in front of the passenger seat for protecting the passenger from injury. Basically, the driver air bag system is requisite, and the passenger air bag system is optional; however, vehicles with passenger air bag systems basically mounted therein for protecting passengers from injury are on the increase in recent years.
FIG. 1 is a perspective view showing a conventional passenger air bag system, FIG. 2 is a front view, in section, showing the conventional passenger air bag system, and FIG. 3 is a side view, in section, showing the conventional passenger air bag system.
As shown in FIGS. 1 to 3, the conventional passenger air bag system for vehicles comprises: an air bag housing 4 mounted to an instrument panel 2; an inflator 6 attached to the rear part of the air bag housing 4 for discharging gas when a collision of the vehicle occurs; a cushion 8 accommodated in the front part of the air bag housing 4 such that the cushion 8 is expanded to the front of a passenger seat by means of gas discharged from the inflator 6; and a retainer 10 attached to the air bag housing 4 between the cushion 8 and the inflator 6 for supporting the cushion 8, the retainer 10 having a plurality of gas-guiding holes 10a for guiding gas discharged from the inflator 6 to the cushion 8.
The air bag housing 4 comprises: a cushion housing 12 formed in the shape of a box with the front part opened so that the cushion 8 is accommodated in the cushion housing 12 while being folded; and a can housing 14 connected to the rear part of the cushion housing 12, in which the inflator 6 is disposed.
The cushion housing 12 is provided at both longitudinal sides thereof with flanges 12a, respectively, which are fixed to the rear part of the instrument panel 2 by means of bolts. At the instrument panel 2 is formed a cut line 2a so that the instrument panel 2 is easily and smoothly broken along the cut line 2a by means of the expanding pressure of the cushion 8.
The can housing 14 is connected to the rear part of the cushion housing 12 in such a manner that the can housing 14 communicates with the cushion housing 12. The can housing 14 is provided at the outside thereof with a mounting bracket 16, which is fixed to a cowl cross member 18 by means of a bolt.
The inflator 6 is formed in the shape of a cylinder. The inflator 6 is provided on the outer circumference at one side thereof with a plurality of gas-discharging holes 20 for discharging gas when a collision of the vehicle occurs.
At one end of the inflator 6 is formed a fixing protrusion 22 having a male screw thread part formed on the outer circumference thereof, on which a fixing nut 24 is rotatably fitted so that the inflator 6 is attached to the side of the can housing 14. At the other end of the inflator 6 is formed a connector coupling member 26 in such a manner that the connector-connecting member 26 is protruded outwardly. To the inflator 6 is connected a connector 28, by which the inflator 6 is linked to an external component, through the connector-connecting member 26.
The connector 28 is disposed outside the air bag housing 4. One end of the connector 28 is connected to the connector-connecting member 26 via a wire 28a, and the other end of the connector 28 is connected to an electronic control unit and a power supply terminal via the wire 28a. 
When a collision of the vehicle is detected by means of a collision-detecting sensor (not shown) mounted to the vehicle, an operation signal is transmitted from the electronic control unit to the inflator 6 via the connecter 28. The inflator 6 is exploded by means of electric current supplied from the power supply terminal for discharging gas having more than a prescribed pressure through the gas-discharging holes 20.
The inlet part of the cushion 8 is disposed between the retainer 10 and the can housing 14, and is attached to the can housing 14 together with the retainer 10 by means of bolts so that the cushion 8 can be fixedly supported by means of the retainer 10.
In the conventional passenger air bag system for vehicles with the above-stated construction, the operation signal is transmitted from the electronic control unit to the inflator 6 via the connector 28 when a collision of the vehicle occurs, and then the inflator 6, to which electric current is supplied from the power supply terminal, is exploded to discharge gas through the gas-discharging holes 20.
The gas discharged from the inflator 6 flows along the can housing 14 so that the gas is supplied into the cushion 8 through the gas-guiding holes 10a of the retainer 10. The cushion 8 is expanded to the front of the cushion housing 12 by means of the gas supplied into the cushion 8.
The instrument panel 2 is broken along the cut line 2a formed at the instrument panel 2 by means of the cushion 8 expanded as described above. Subsequently, the cushion 8 is expanded toward a passenger seated in the passenger seat, whereby shock transmitted to the passenger is effectively absorbed, and thus injury to the passenger is minimized.
In the conventional passenger air bag system for vehicles, however, the inflator 6 is horizontally disposed in the can housing 14, and the gas-discharging holes 20 are formed adjacent to one end of the inflator 6. As a result, the cushion 8 is eccentrically expanded by means of the gas discharged through the gas-discharging holes 20 when a collision of the vehicle occurs.
In other words, the gas discharged through the gas-discharging holes 20 eccentrically formed at the inflator 6 is not uniformly supplied into the cushion 8 with the result that the expansion shape of the cushion differs from the designed shape of the cushion. Consequently, the cushion 8 expanded to the front of the passenger seat performs an incomplete shock-absorbing function, whereby safety and reliability of the air bag system are deteriorated.